Thru Hull Exhaust Install

[ta2dfyrman]

I recently aquired for a decent price Corsa manual exhaust diverters and bought some 4" straight cut tips with internal flaps. I have all boots and clamps i need, just want to be certain I have covered all angles.
I am going to run it thru hull and out drive. I already have a 4" hole saw to drill holes and am gonna tape off to prevent cracking gel. Of course I will measure 10 times, and figure start cut from outside in. I have marine tek, epoxy and 5200. I have heard the different replies about 5200,so I know. I guess use epoxy to seal inside cut? floowed of course by sealing tips. I guess my only question is relocating water line from lower unit to exhaust risers? Take out bolt insert nipple and attach which line? Or is that no necessary? Thanks for any help and hopefully not to much critisism. IK will try to attach a couple pics if I can upload them from cell phone in the next couple minutes. Oh and I am running 5.7 chevy 350EFI with alpha 1 outdrive if it is factor. Thanks again to all, you are a great help.

[fogducker III]

Is there a Y pipe already installed? If not, I think your install job is bigger then you think....engine has to come out if there is no pipe....

[CHACHI]

Epoxy is good to seal the 4" holes, but if you could remove say an 1/8 inch of coring and then fill the gap with filled epoxy that would be better.

Use silicone to mount the tips, you may want to remove them in the future.

Ken

[The Hedgehog]

Is there a Y pipe already installed? If not, I think your install job is bigger then you think....engine has to come out if there is no pipe....

If I read it right, he already has the ypipe and wants to add the diverters. Been there and done that but mine had a Bravo setup.

Like Chachi said, epoxy the inner holes and use silicone. No 5200 if you ever want to get them out again.

[ta2dfyrman]

Y pipe as far as i know is there. Pipe runs off of risers and connects behind motor. It has oval connection that matches that on the bottom of the diverter. It just ties in there correct and then two out the rear transom. It has factory set up at moment that goes through outdrive. No mods.
I think I have a clue how to do this, just take my time. I guess where my uncertainty is in the water line. I guess if dont run through riser then it is considered dry, and my exhaust temps might run considerably higher?

[ta2dfyrman]

I think I uploaded some pics. We will see. First is motor with lines off front, 2nd and 3rd should be risers. Straight shot out rear with exception of right side relocating gear oil reservoir up or right a couple inches.

[mrfixxall]

First things first!

Merc makes a pattern and ill post a pic of it so you can get the measurements..Cut a hole in a piece of plywood first and make sure you have enough play room to mount the tips, i usually use a 4 1/8'' hole saw..After the holes are cut paint the bare wood and fiberglass from the holesaw, use a sealer from west marine called life seal,this way they can be removed without destroying the gel and fiberglass..

Before you remove the risers try to remove the 80* elbow first,this way if you have the dry joint exhaust it wont cost you 100 bucks for the gaskets..if you slide the rubber exhaust bellow down far enough on the y pipe you should be able to slide them back off the risers..all else fails then unbolt them but drain the manifolds first..When you go to cut the holes with the hole saw drill a pilot hole first and take your measurements inside the boat to make sure everything is going to line up..now when your ready to use the hole saw run the drill backwards until you get through the gel,also apply masking tape over the area your cutting with the hole saw..

Good luck!

[fogducker III]

Sorry, my bad, read it wrong......:bonk:

Follow Fix's info and you will be good to go....:crossfing:

[ta2dfyrman]

Fixx apreciate the pics. I wonder if I could order that from any where. Cause actually didn't see a measure on there for top of outdrive to centerline of hole. If you follow what I'm asking? Cause basically if I had that I could run up outdrive to center and the the 12 and whatever inches out in each direction. But thx alot again it will help out. I'm sure it's just patience and precise measurements

[mrfixxall]

Fixx apreciate the pics. I wonder if I could order that from any where. Cause actually didn't see a measure on there for top of outdrive to centerline of hole. If you follow what I'm asking? Cause basically if I had that I could run up outdrive to center and the the 12 and whatever inches out in each direction. But thx alot again it will help out. I'm sure it's just patience and precise measurements


Its on the first pic, 12 5/8 '' from the crankshaft centerline.. you can click on the pic several times to blow it up..it the tips wont cleat the rub rail area you may have to trim the top portion of the ring on the tip.

[ta2dfyrman]

Ohh. Ok sorry fixx I'm checking this from my iPhone so I didn't see it. I will check it all again when I get home. Is there any sort of landmark to mark the center(ie line,bolt,etc)?

[mrfixxall]

Read the first pic when you get home, its like a blueprint and gives you all the measurements..start out with a small drill bit and drill a small hole after you get the measurements all marked out on the transom,then go inside the boat and check from the center od the hole to the center of the riser,you want a slight angle down towards the tips so the water can drain..

[justleft]

I once did a Scarab where nothing was standard.

Mock it up with 4" PVC or thin wall metal tubing.
That way you will know where and at what angle to drill the transom.
In my case the angle was not 90 to the transom.

I sure had to take a deep breath before drilling the 1st hole.

All 4 came out right on the money !!!!

[ta2dfyrman]

I decided due to the fact I would like to use boat Friday and saturday, I will postpone project till bright and early Monday. So I have all measurements and tools.And also the epoxy and sealant have proper curing time. Thx for help I guess I will post pics of success or disaster however it turns.......

[Just Say N20]

Viewable pics.

[MOP]

Why not do it the easy way? Take a piece of exhaust hose long enough to reach from the riser to the transom mark around it with a pencil, the find center and mark it. Now take a 1/4" drill and drill your pilot from the inside, that will get you spot on without all the rigger maroe! Life can be simple!

[ta2dfyrman]

Okay just wanna recheck with the pros. I took off the right side and ran into a little glitch. When I slide diverter on it doesnt match up with lower y pipe. I think i need to trim the front considering the factory down pipe is about 1 1/2 shorter. just want a little advice. I might also have to trim a little off lower. Attched a pic. The port side is correct length but down could use half inch trim. The starboard factory pipe is longer, so could use a cut and also half in trim of bottom. Appreciate any input before i start cutting. Sorry about pic. Iphone??? thx

[ta2dfyrman]

Lets try pics again...

[mrfixxall]

sounds like you have a set from a big block..measure teice and cut once.. and remember bouble clamps at every joing connection

[ta2dfyrman]

Yeah thats what im assuming fixx. Im gonna take inch and half of length of starboard. The port lenth is good. And 3/4 inch of bottoms of both. Now dilemma is cutting it. What do i need? I tried a hacksaw for laughs.....it wasnt funny. Thx for the help and fast response..

[mrfixxall]

Yeah thats what im assuming fixx. Im gonna take inch and half of length of starboard. The port lenth is good. And 3/4 inch of bottoms of both. Now dilemma is cutting it. What do i need? I tried a hacksaw for laughs.....it wasnt funny. Thx for the help and fast response..


if you have a 4 1/2 grinder use a cutting disc,,they sell them at home depot for about 2 bucks each,but a few of them because stainless steel dont cut so easy..make sure you have the proper backing plate for the wheel..the cut off wheel is around 1/16'' thick.

BTW the corsa tip will fit over the exhaust and sometimes will butt up to the outside of the riser..also make sure theirs no interferance with the flap on the inside of the corsa and the far end tip of the riser.

[ta2dfyrman]

Yeah took it over to a steady handed pro. We got em cut and they fit like a glove. Now after the rain stops the fun can begin with the exhaust hole cuts. Yeah i accounted for the buttn up part in my cut.. Thanx for the heads up..One thing I do notice is yes the tops of cut are gonna be close to rub rail(which I have searched forums and seems normal) But also the outside half inch inch is gonna run where the rear hull bevels down from thick to thin? I imagine as long as i epoxy seal it really well there should be no problems? and of course seal the tips and screwholes for tips..

[ta2dfyrman]

Well finally done...I think. Wound up dropping tips a little to clear rub rail. Made it a little awkward connecting on the inside but with a little convincing it all came together. Double clamped all connections and sealed the tips after epoxy on holes dried..Guess I will run it wednesday or thursday and check for leaks and retighten clamps. Anything anyone can think to recheck or do??Much appreciate all the help so far

[mrfixxall]

Well finally done...I think. Wound up dropping tips a little to clear rub rail. Made it a little awkward connecting on the inside but with a little convincing it all came together. Double clamped all connections and sealed the tips after epoxy on holes dried..Guess I will run it wednesday or thursday and check for leaks and retighten clamps. Anything anyone can think to recheck or do??Much appreciate all the help so far


looks like it turned out well,nice job:)..just make sure those tips have internal flappers or the rubber ones on the end,, if a big wave hits the back of the boat you may get some water through the exhaust valves that are open and fill the cylinders.

[ta2dfyrman]

Thanks. Yeah they are hardin marine,have internal flappers..

[justleft]

Oh yea ! Looks great !

[ta2dfyrman]

Well finally got it in water yesteday. It sounds about perfect, not to loud and just enough purrr.. Gotta try to figure out how to upload little clip off of my cell phone.
Quick question if anyone knows. I know its y piped so not alot of water will come out pipes. But is it normal for more water to come out of one pipe than the other? I put my hand up to them and they feel about same pressure, but wanna make sure there is nothing that is gonna mess up down the road if I dont check it now. Thermostat runs 150 all day so?

[mrfixxall]

Well finally got it in water yesteday. It sounds about perfect, not to loud and just enough purrr.. Gotta try to figure out how to upload little clip off of my cell phone.
Quick question if anyone knows. I know its y piped so not alot of water will come out pipes. But is it normal for more water to come out of one pipe than the other? I put my hand up to them and they feel about same pressure, but wanna make sure there is nothing that is gonna mess up down the road if I dont check it now. Thermostat runs 150 all day so?


i dont know which thermostst housing you have but their are plastic balls with springs at the end under the hoses..which ever side has more wter coming out you tighten to get even flow out the tips.

[donzi4life]

looks good where did you get the y-pipe from?

[ta2dfyrman]

Actually found them on craigslist. The apparently were on big block and just a little cutting and they fit good. Dont know if your looking for a pair but a friend informed me if you type in craigslook.com it searches the entire U.S. Helps alot

[MOP]

i dont know which thermostst housing you have but their are plastic balls with springs at the end under the hoses..which ever side has more wter coming out you tighten to get even flow out the tips.

Fix the nylon balls in that series of Tstat are on a common rod there is no way for them not to have equal pressure, they may have to much or to little but never unequal. He will need to look at other parts of the system to determine the unevenness of flow.

[ta2dfyrman]

And Fixx. I took off hoses and no springs or screws just flows straight through. Just got gaskets so gonna go get boat tomorrow and take risers off and clean them out so maybe I can get a little more time out of them.
So now the big question which has pretty much been answered in other forums. Manifolds and new risers? Stainless of course? Where is my best bang for the buck? Dont plan on adding any more horses so where is the best to look for small block risers?
I attached pic of riser, what you think on rust alot or normal?

[The Hedgehog]

And Fixx. I took off hoses and no springs or screws just flows straight through. Just got gaskets so gonna go get boat tomorrow and take risers off and clean them out so maybe I can get a little more time out of them.
So now the big question which has pretty much been answered in other forums. Manifolds and new risers? Stainless of course? Where is my best bang for the buck? Dont plan on adding any more horses so where is the best to look for small block risers?
I attached pic of riser, what you think on rust alot or normal?

If you want to keep the silent choice, you will need to go with manifolds. Stainless Marine is a great choice for that.

[ta2dfyrman]

Yeah well I have spent last couple days searching internet at manifolds/risers. The guy that worked on my boat before I bought it said due to salt and brackish water I am in to either stay with cast iron due to cost or stainless. But manifolds on stainless marine appear to be aluminum? Now how will the aluminum react with the brackish salt water. If they are gonna wear as fast as iron i guess I should stick with cast? What is avg pricing for stainless set up?
I have searched this donzi forum so much in the last two weeks on topics I think my head is gonna explode.LOL
Oh and I did check with him and the thermostat is a 160* with no adjusting screws just flows both ways.